Partly this is a matter of personal preference - albeit one that's inevitably influenced by the prevailing wind of fashion - but mainly this is a question of proportion. If Harvey were to wear a skinny tie (say two inches wide) with his suits, which have broad shoulders and wide lapels, the outfit would be comically imbalanced, as it would be if Mike were to wear a three-inch wide tie with his slim suits. Of course the height, weight and shape of the wearer himself must also be taken into account. Broader men might consider avoiding particularly wide ties, to help create an illusion of lean length, while very skinny ties on a thin guy can create a rather willowy look - not ideal for a power player.